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GoodbyeDPI/src/ttltrack.h

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Automatic TTL value picker for --set-ttl Fake Packet mode This is a per-connection (per-destination) automatic TTL adjusting feature. Basically a --set-ttl mode where you don't need to set specific TTL value. It works as follows: 1. All incoming SYN/ACKs (the response to client's SYN) are intercepted 2. TTL value is extracted from SYN/ACK 3. New TTL is calculated with the simple formula: 128 > extracted_ttl > 64: // Server is running Windows fakepacket_ttl = 128 - extracted_ttl - decrement 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other fakepacket_ttl = 64 - extracted_ttl - decrement 4. Fake packet is sent To comply with the multi-path multi-hop server connections where 1 hop dispersion is not rare, decrement should be at least of value "2", which is the default. The patch does not process "too strange" TTL values (bigger than 128, less than 34).
2021-12-25 08:13:50 +00:00
#ifndef _TTLTRACK_H
#define _TTLTRACK_H
#include <stdint.h>
#include "dnsredir.h"
typedef struct tcp_conntrack_info {
uint8_t is_ipv6;
uint8_t ttl;
uint32_t srcip[4];
uint16_t srcport;
uint32_t dstip[4];
uint16_t dstport;
} tcp_conntrack_info_t;
Fix all the warnings and notes
2021-12-26 14:33:39 +00:00
int tcp_handle_incoming(uint32_t srcip[4], uint32_t dstip[4],
uint16_t srcport, uint16_t dstport,
uint8_t is_ipv6, uint8_t ttl);
Automatic TTL value picker for --set-ttl Fake Packet mode This is a per-connection (per-destination) automatic TTL adjusting feature. Basically a --set-ttl mode where you don't need to set specific TTL value. It works as follows: 1. All incoming SYN/ACKs (the response to client's SYN) are intercepted 2. TTL value is extracted from SYN/ACK 3. New TTL is calculated with the simple formula: 128 > extracted_ttl > 64: // Server is running Windows fakepacket_ttl = 128 - extracted_ttl - decrement 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other fakepacket_ttl = 64 - extracted_ttl - decrement 4. Fake packet is sent To comply with the multi-path multi-hop server connections where 1 hop dispersion is not rare, decrement should be at least of value "2", which is the default. The patch does not process "too strange" TTL values (bigger than 128, less than 34).
2021-12-25 08:13:50 +00:00
Fix all the warnings and notes
2021-12-26 14:33:39 +00:00
int tcp_handle_outgoing(uint32_t srcip[4], uint32_t dstip[4],
uint16_t srcport, uint16_t dstport,
Automatic TTL value picker for --set-ttl Fake Packet mode This is a per-connection (per-destination) automatic TTL adjusting feature. Basically a --set-ttl mode where you don't need to set specific TTL value. It works as follows: 1. All incoming SYN/ACKs (the response to client's SYN) are intercepted 2. TTL value is extracted from SYN/ACK 3. New TTL is calculated with the simple formula: 128 > extracted_ttl > 64: // Server is running Windows fakepacket_ttl = 128 - extracted_ttl - decrement 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other fakepacket_ttl = 64 - extracted_ttl - decrement 4. Fake packet is sent To comply with the multi-path multi-hop server connections where 1 hop dispersion is not rare, decrement should be at least of value "2", which is the default. The patch does not process "too strange" TTL values (bigger than 128, less than 34).
2021-12-25 08:13:50 +00:00
tcp_conntrack_info_t *conn_info,
Fix all the warnings and notes
2021-12-26 14:33:39 +00:00
uint8_t is_ipv6);
Automatic TTL value picker for --set-ttl Fake Packet mode This is a per-connection (per-destination) automatic TTL adjusting feature. Basically a --set-ttl mode where you don't need to set specific TTL value. It works as follows: 1. All incoming SYN/ACKs (the response to client's SYN) are intercepted 2. TTL value is extracted from SYN/ACK 3. New TTL is calculated with the simple formula: 128 > extracted_ttl > 64: // Server is running Windows fakepacket_ttl = 128 - extracted_ttl - decrement 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other fakepacket_ttl = 64 - extracted_ttl - decrement 4. Fake packet is sent To comply with the multi-path multi-hop server connections where 1 hop dispersion is not rare, decrement should be at least of value "2", which is the default. The patch does not process "too strange" TTL values (bigger than 128, less than 34).
2021-12-25 08:13:50 +00:00
Better Auto TTL adjusting algorithm which honors short distance Say you set --auto-ttl to 4. If the TTL distance to the destination host is too short, say 6, auto-ttl would decrease it by 4 and send a fake packet with TTL 2, which is too low for the packet to travel via DPI system. But if you set --auto-ttl to a lower value such as 2, that may introduce issues over long lines where outgoing-path TTL and incoming-path TTL may have difference more than 2 hops due to higher chance of assymetric routing along the path. To solve this issue, this commit introduce auto-ttl range of two values. If the incoming TTL distance is more than autottl2, it is subtracted by autottl2 value. If the distance is less than autottl2, the distance value is used as a normalized weigth of [autottl1; autottl2] scale. The simplified formula is as follows: 128 > extracted_ttl > 98: // Server is running Windows nhops = 128 - extracted_ttl 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other nhops = 64 - extracted_ttl if (nhops - autottl2 < autottl2) ttl_of_fake_packet = nhops - autottl1 - trunc((autottl2 - autottl1) * ((float)nhops/10)); else ttl_of_fake_packet = nhops - autottl2
2021-12-28 13:37:42 +00:00
int tcp_get_auto_ttl(const uint8_t ttl, const uint8_t autottl1,
Add Fake Packet maximum TTL limit to Auto TTL mode This patchset adds maximum TTL size of the fake packet to be sent, to further improve compatibility with asymmertic routing and non-standard TTL value set on servers.
2021-12-28 23:01:51 +00:00
const uint8_t autottl2, const uint8_t minhops,
const uint8_t maxttl);
Automatic TTL value picker for --set-ttl Fake Packet mode This is a per-connection (per-destination) automatic TTL adjusting feature. Basically a --set-ttl mode where you don't need to set specific TTL value. It works as follows: 1. All incoming SYN/ACKs (the response to client's SYN) are intercepted 2. TTL value is extracted from SYN/ACK 3. New TTL is calculated with the simple formula: 128 > extracted_ttl > 64: // Server is running Windows fakepacket_ttl = 128 - extracted_ttl - decrement 64 > extracted_ttl > 34: // Server is running Linux/FreeBSD/other fakepacket_ttl = 64 - extracted_ttl - decrement 4. Fake packet is sent To comply with the multi-path multi-hop server connections where 1 hop dispersion is not rare, decrement should be at least of value "2", which is the default. The patch does not process "too strange" TTL values (bigger than 128, less than 34).
2021-12-25 08:13:50 +00:00
#endif
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